It is known from the prior art to provide electrical lamp sockets molded from an electrically insulating material, wherein the side electrode and the bottom electrode by which a light bulb is energized are inserted within the mold and firmly anchored within the molded socket during the molding process. The side electrode may be of a type which includes inwardly extending edge-on protrusions profiled to engage the threads of the screwing portion, i.e. the screw cap, of the light bulb.
The side electrode functions both to provide an electrical contact, and also to mechanically locate and retain the light bulb within the socket. Accordingly, the side electrode is profiled to engage the screw cap of the light bulb over an appreciable axial length thereof. Generally speaking, in light bulbs of this nature, there are some three complete turns of thread around the screw cap, and the side electrode is formed by first and second diametrically opposed portions each provided with three protrusions which engage the troughs between the threads.
Increasingly, the screw caps of light bulbs are being formed from aluminum, whereas the edge-on side electrodes are formed from brass. It is often found that shaving of the screw cap takes place as the light bulb is being screwed into or out of the electrical lamp socket. Where the electrical lamp sockets are used out-doors, some oxidation of the screw caps may occur. Both shaving and corrosion promote the jamming of the light-bulb in the socket. When excessive force is applied to the glass envelope of the light bulb in an endeavour to unjam it, breakage may ensue. It is also possible for the shavings to bridge between the electrodes, thereby creating a potential hazard.
In the prior art lamp sockets, whether of conventional design or of the edge-on type, when a lamp is being inserted into a socket, electrical contact is made between the screw cap and the side electrode while an appreciable portion of the screw cap is located outside of the confines of the electrical lamp socket, thereby creating a further potential hazard.